1. Field of the Invention
The present invention relates to a digital camera for shooting a desired subject and outputting a digital image signal representative of the subject. More particularly, the present invention relates to a digital camera capable of sending an image signal for a framing purpose, and an image reproducing device connectable to the digital camera for outputting the image signal.
2. Description of the Background Art
A recent achievement in the imaging art is a digital camera capable transforming an image signal output from a CCD (Charge Coupled Device) image sensor or similar solid state imaging device to digital image data, and recording the digital image data in a memory card or similar recording medium, With an advanced type of digital camera, it is possible to read image data out of a recording medium and feed them to a television (TV) receiver, personal computer or similar output terminal so as to reproduce and display an image represented by the image data.
A digital camera including a CCD image sensor having, e.g., about 400,000 pixels is conventional. When image data output from this kind of digital camera are sent to the outside at a rate of about 14 MHz, i.e., a so-called TV rate, an image represented by the image data can be reproduced as a substantially real time image. However, when such an image is printed, a sufficiently high resolution is not achievable. In light of this, a CCD image sensor having about 1,300,000 pixels may be used in order to shoot a scene with a resolution high enough to be fit for, e.g., printing and send the resulting image data. This kind of scheme, however, prevents the image being shot from being sent in a real time fashion. As a result, even if the image data are displayed on a monitor of TV level, frames are partly lost, making it difficult for a person to perform framing while watching a real time image being shot.
It is therefore an object of the present invention to provide a digital camera capable of implementing real-time image transfer to the outside of the camera in order to allow a person to perform framing while monitoring an image, and to provide an image reproducing device connectable to the camera.
It is another object of the present invention to provide a digital camera capable of outputting image data having a high pixel density, and an image reproducing device connectable to the camera.
In accordance with the present invention, a digital camera for shooting a subject and outputting a digital image signal representative of the subject includes an imaging device selectively operable, in response to a drive signal, in a partial pixel read mode for outputting an image signal in which pixels constituting the image of the subject are reduced, or in a full pixel read mode for outputting an image signal having all of the pixels. A converting circuit converts each of the image signals selectively output from the imaging device to a digital image signal. A signal processing circuit processes the digital image signal. An outputting circuit outputs the image signals selectively output from the imaging device. A control circuit controls the operation of the digital camera. The control circuit selects either one of the partial pixel read mode and full pixel read mode and feeds a drive signal to the imaging device for causing it to operate in the mode selected. The outputting circuit includes a transmitting circuit for transmitting via a communication channel a first image signal output from the imaging device in the partial pixel read mode and then output from the signal processing circuit, while guaranteeing the data rate of the image signal, or transmitting via the communication channel a second image signal output from the imaging device in the full pixel read mode and then output from the signal processing circuit, and a recording circuit for recording the second image signal in a storage medium removably connected to a connector. The control circuit feeds the first image signal to the transmitting circuit to thereby sequentially transmit the first image signal via the communication channel. The control circuit sets up the full pixel read mode in response to a release command input by an operator to thereby feed the second image signal to either one of the first transmitting circuit and recording circuit.
Also, in accordance with the present invention, an image reproducing device is connectable to a digital camera via a communication channel. The digital camera includes an imaging device for shooting a subject and selectively operable, in response to a drive signal, in a partial pixel read mode for outputting an image signal in which pixels constituting the image of the subject are reduced, or in a full pixel read mode for outputting an image signal having all of the pixels. A converting circuit converts each of the image signals selectively output from the imaging device to a digital image signal. A signal processing circuit processes the digital image signal. A first transmitting circuit transmits via the communication channel a first image signal output from the imaging device in the partial pixel read mode and then output from the signal processing circuit, while guaranteeing the data rate of the first image signal, or transmits via the communication channel a second image signal output from the imaging device in the full pixel read mode and then output from the signal processing circuit. A control circuit controls the operation of the digital camera. The control circuit selects either one of the partial pixel read mode and full pixel read mode and feeds a drive signal to the imaging device for causing it to operate in the mode selected. The control circuit feeds the first image signal to the first transmitting circuit to thereby sequentially transmit the image signal via the communication channel. The control circuit sets up the full pixel read mode in response to a release command input by an operator to thereby feed the second image signal to either one of the first transmitting circuit and recording circuit. The image reproducing device includes a second transmitting circuit for receiving the first image signal via the communication channel, and transmitting an acknowledgement of receipt to the digital camera via the communication channel. An outputting circuit outputs the first and second image signals received by the second transmitting circuit.